1. Field of the Invention
The present invention relates to a light-emitter that takes advantage of an electroluminescence phenomenon of an organic material, a method of manufacturing the same and a light-emitting device.
2. Description of the Related Art
In recent years, an organic electroluminescence element (hereinafter referred to as “organic EL element”) has been studied and developed. The organic EL element is a light-emitter that takes advantage of an electroluminescence phenomenon of an organic material. The organic EL element has a structure in which an organic light-emitting layer is positioned between an anode and a cathode. A hole is injected from the anode and an electron is injected from the cathode. In this way, the hole and the electron are recombined in the organic light-emitting layer. This is how the organic EL element emits light. Note that a form of the light-emitting layer is defined by a bank that is formed with use of an insulating material.
Between the anode and the organic light-emitting layer is provided any of layers such as a hole-injection layer, a hole-transport layer and a hole-injection/transport layer, as needed. Between the cathode and the organic light-emitting layer is provided any of layers such as an electron-injection layer, an electron-transport layer and an electron-injection/transport layer, as needed. Hereinafter, the hole-injection layer, the hole transport layer, the hole-injection/transport layer, the electron-injection layer, the electron-transport layer and the electron-injection/transport layer are collectively referred to as a “charge-injection/transport layer”.
A charge-injection/transport layer of a conventional organic EL element is formed with use of a conductive polymer material such as PEDOT (a mixture of polythiophene and polystyrene sulfonate) as shown in the following chemical formula 1 (see Patent Literature 1, for example).

In recent years, technology has been developed in which the charge-injection/transport layer is formed with use of metal oxide such as transition metal oxide in place of the PEDOT (see Patent Literatures 2 and 3, for example). An organic EL element having the charge-injection/transport layer formed with use of the metal oxide generally has the following advantages compared to the organic EL element having the charge-injection/transport layer formed with use of the PEDOT. One of the advantages is that the organic EL element has an excellent voltage-current density property. The other advantage is that the organic EL element is less likely to deteriorate even if a large current is applied to increase light-emitting intensity.
3. Patent Literatures    [Patent Literature 1] Japanese Patent Application Publication No. 2007-527542.    [Patent Literature 2] Japanese Patent Application Publication No. 2007-288071.    [Patent Literature 3] Japanese Patent Application Publication No. 2005-203339.